package club.pchome.utils;

import java.util.Random;

public class MathUtil {


    //随机生成六位数，并且每位数都不重复

    /**
     *
     * @return
     */
    public static int Num( Integer numLen) {
        numLen = null==numLen ? 6 : numLen;
        int[] array = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9};
        Random rand = new Random();
        for (int i = 10; i > 1; i--) {
            int index = rand.nextInt(i);
            int tmp = array[index];
            array[index] = array[i - 1];
            array[i - 1] = tmp;
        }
        int result = 0;
        for (int i = 0; i < numLen; i++) {
            result = result * 10 + array[i];
        }
        if (String.valueOf(result).length() == numLen) {
            return result;
        } else return Num(numLen);
    }

}
